Tap system for molten materials

ABSTRACT

A continuous tap system for molten materials issuing from the well of a vertical shaft incinerator operating under positive pressure includes a conduit which is formed from refractory material and further includes a means for cooling the refractory material to control the corrosion of the refractory material caused by flowing molten material.

TAP SYSTEM FOR MOLTEN MATERIALS BACKGROUND OF THE INVENTION In U.S. Pat. No. 3,511,194 by K. W. Stookey entitled Method and Apparatus for High Temperature Waste Disposal, waste materials are charged to the upper portion of a vertical chamber for movement downwardly and a hot blast is supplied to a lower portion of the chamber for movement upwardly. The noncombustible portions of the refuse which may consist of metal, glass, and various types of ash, stone, dirt, etc., are heated to their melting and flow points by the heat released from the first stage combustion in the vertical chamber and are continuously drained, or tapped from the hearth of the vertical chamber or gasifier.

Since the hearth area operates under a positive pressure, large quantities of highly heated gaseous products at hearth pressure can escape through the tap hole creating a loss of these products unless a seal is maintained to retain them. The escape of these superheated gases not only would reduce the efficiency of the process but create a dangerous area in the vicinity of an open tap hole.

In disposing of refuse by the method disclosed in the above-identified U.S. Pat. No. 3,511,194, a -variable charge of refuse is continuously added to the vertical shaft gasifier. Batch slaggng as conventionally carried out in metallurgical furnaces is impractical in the above method since plant shutdown during the tapping period with its attendant troubles would be encountered. When the hearth area is tapped continuously the flow of slag may vary from a trickle to. a large flow. With either condition, slag cooling starts to take place as soon as the slag leaves the influence of the hot hearth or well zone. The cooling of the slag results in an increase of its viscosity which can reach the point of soliditication thereof within the tap hole which can completely block the tap hole.

The slag which results from the gasification of refuse is particularly corrosive. As corrosive slag erodes and enlarges the tap hole, the repair or replacement of refractory material is necessitated.

Heretofore, refractory taps alone for this type of molten material have been ineffectivein surmounting one or more of the above problems. l

SUMMARY OF THE INVENTION In a tap for the discharge of molten material formed in the well of the incinerator, a runner or conduit is formed from refractory material and includes a means for cooling the refractory from'beneath that comes into contact with the flowing, highly corrosive slag, in order to inhibit the corrosion and erosion beyond acceptable depth.

Because of the heat losses occasioned by the cooling of the refractory and losses from other sources, the slag may become too viscous to flow properly. Therefore, strategically placed supplementary burners are used in such a way as to heat and cause the slag to drop freely from the discharge end of the runner, through a pipelike chamber, the lower end of which is immersed in water to form a gas seal to preclude the escape of gases controlling corrosion and erosion of refractory materials while pennitting a variable flow of slag.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front elevational view of a furnace hearth and slag vtap therefor; y

FIG. 2 is a side elevational view along section 2-2 of FIG. 1; and

FIG. 3 is a detailed view of the water jacket.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT Referring to the drawings in more detail, the lower portion of the vertical shaft gasifier ll is illustrated in FIG. 1. Details of the vertical shaft gasifier 11, apparatus and process for high temperature disposal of waste materials is available by reference to my issued U.S. Pat. No. 3,51 1,194, hereinbefore discussed. The hearth 13 of gasifier l1 may include a number of tuyeres (not shown) which are circumferentially spaced around the base of the hearth 13. A bustle pipe (not shown) connects the tuyeres to a source of air. Although the tap of the present invention is ideally suited for a gasifier as described in the aforementioned patent application, it is not intended that use of the tap be limited thereto. The tap of the present invention is paricularly suited for conveying many molten materials from any chamber containing those materials.

The hearth 13.at the base gasifier 11 contains a plurality of openings l5 as illustrated in FIG. 2, for the flow of air for combustion. The openings can accommodate tuyeres hereinbefore discussed. In accordance with principles of the present invention, the well or hearth 13 has one or more tap systems 17 which serve as an outlet for molten material which is drained from the gasifier 1l.

The hearth 13 of the furnace or gasifier l1 has a lining of refractory materials 19 within a metal housing 2l. The tap system 17 includes a housing 23 of metal construction in sealing relationship with a tap hole or outlet opening 25 in the lower portion of the hearth 13. The housing 23 has a refractory lining or walls 27 forming a conduit 29 as illustrated in FIG. 2. The lining 27 comprises a plurality of refractory bricks 31 arranged so as to provide a tapered conduit 29 having a bottom 33 gradually inclined downwardly from the opening 25. The conduit 29 is connected at one end to the hearth 13 or source of molten material and communicates with a chamber 35 at the other end. The discharge end of the conduit includes a lip 37 projecting into the chamber 35 so molten material or slag flows over the lip 37 and falls through the chamber 35 without flowing along the walls 39 of the chamber 35.

Heating means are provided within the tap system 17 for maintaining a viscous flow of molten material or slag thereby preventing soliditication of the slag and blockage of the tap system 17. Preferably at least one heating means 53 is provided for heating the area above the conduit 29 to maintain the viscous flow of an upper portion of molten material. Preferably another heating means 55 is provided in the chamber 35vbelow the lip 37. The heating means 53 and 55 are preferably gas burners. The heating means 53 and 55 are disposed so that the products of combustion compensate for heat losses and maintain a viscous flow of material.

The chamber 35 through which the slag falls is a vertical tube immersed in a liquid 57. As the molten material drops into the cooling liquid 57 which is preferably water, the molten slag is suddenly chilled and caused to break into small particles, generally known as frit. The frit settles to the bottom of a vessel 59 containing the water where it may be removed.

The vessel 59 for receiving the solid particles of molten material can be open at the top. The lower erid of the vessel 59 is tapered inwardly from vertical walls 63 to a suitable discharge opening 65 at the bottom which includes a means for continuously removing frit such as a valve 67. The valve 67 can be turned continuously to permit the removel of solid materials with a minimal loss of liquid 57. A line 69 having a valve 71 is provided for make-up liquid. An overflow line 73 is provided for maintaining a constant level of liquid 57 lin the vessel 59.

In accordance with the principles of this invention, a cooling means is spaced from the bottom of conduit 29 and in contact with the refractory material forming the lining 27 so as to cool the refractory material from beneath thereby controlling the corrosion caused by flowing molten material. As illustrated in detail in FIG. 3, the cooling means is a container 43 which has an inlet iine 45 and outlet line `47 for the circulation of a'coolant such as water therethrough. The container 43 may be a variety of shapes depending on the cooling effect desired which are preferably baffled.

As illustrated in FIG. 3, the container 43 has a side 49 facing the conduit 29 so as to present a large surface area for heat exchange. The container 43 is disposed within a pocket or opening 5l in the lining 27 of refractory material sufficiently close to the conduit 29 so that the cooling effect of the container 43 is effective i-n reducing corrosion of the conduit 29 due to the fluxing action of molten material. The container 43 is in sufficient proximity to the lip 37 so as to preserve the integrity of a lip 37 thereby permitting the slag to drop through thev chamber` 35 rather than flow along the walls 39. Preferably the corrosion of the lip 37 is limited due to the cooling of refractory material so that the fall of molten slag does not drift from the desired center fall tothe degree that it would cut back and eventually strike the walls 39.

As the slag flowing through the conduit 29 cuts the refractory material, the depth of the cut approaches the point at which a portion of the slag adjacent the refractory lining 27 is cooled. As a result the slag viscosity adjacent the refractory lining 27 is increased and the rate of corrosion decreased. This effect continues until an equilibrium is reached. The cooling causes a portion of the slag to congeal whereby an interface is formed. Then the slag works upon itself and ceases to attack the underlying refractory.

The present invention contemplates a variety of tap systems 17 for conveying molten materials. A variety of cooling means of various shapes cari be disposed along the conduit 29 so as to reduce corrosion in selected areas.

ln operation, the liquid 57 in the chamber 35 prevents the escape of hot gases. As the pressure in the hearth 13 varies the level of liquid 57 in the chamber 35 rises or falls to compensate for the change in pressure. Generally the gasif'ier 1 l is operated under a positive pressure in the hearth 13 and due to a variable charge of waste material the pressure in the hearth 13 can fluctuate rapidly. With the vertical tube immersed in the liquid a sufficient depth to accommodate maximum pressure fluctuations, the escape of combustion gases from the hearth area is prevented. Due to the liquid seal, the conduit 29 is opened to the hearth 13 during the entire operation so as to permit the continual withdrawal of molten material. The burner arrangement maintains the fluidity of the slag while the cooling means limits the corrosion of the refractory material. A teaming hole is disposed above the chamber 35 so as to permit a cleaning of the chamber 35 with a proper tool if any accumulation of slag occurs therein. A peep hole 77 is also illustrated in the drawings so that the erosion of the conduit 29 can be monitored by visual inspection.

While preferred embodiments of this invention have been described and illustrated it is to be recognized that modifications and variations thereof may be made without departing fron .the spirit and scope of this invention as described in the appended claims.

What is claimed is:

1. Ina sealed tap system for the discharge of molten material from a chamber, comprising a downwardly inclined refractory conduit communicating with an opening in said chamber, said conduit adapted to discharge molten material across a lip protruding from the discharge end of said conduit into a chamber immersed in a liquid whereby said molten' material is rapidly quenched by said liquid, the improvement which comprises providing heating'means adapted to maintain the fluid flow of an upper portion of molten material in said conduit and cooling means adapted to congeal a portion of flowing molten material adjacent the refractory conduit so as to reduce the corrosion of the refractory.

2. An improvement as setforth in claim 1, wherein said heating means comprises a burner adapted to dis-v charge hot gases of combustion over the upper portion of said molten material.

3. An improvement as set forth in claim 1, wherein said cooling means is in sufficient proximity to the protruding lip to maintain the integrity thereof.

4. Ari improvement as set forth in claim 3, wherein said cooling means comprises a container adapted for the circulation of water therethrough.

lll li Il il l 

1. In a sealed tap system for the discharge of molten material from a chamber, comprising a downwardly inclined refractory conduit communicating with an opening in said chamber, said conduit adapted to discharge molten material across a lip protruding from the discharge end of said conduit into a chamber immersed in a liquid whereby said molten material is rapidly quenched by said liquid, the improvement which comprises providing heating means adapted to maintain the fluid flow of an upper portion of molten material in said conduit and cooling means adapted to congeal a portion of flowing molten material adjacent the refractory conduit so as to reduce the corrosion of the refractory.
 2. An improvement as set forth in claim 1, wherein said heating means comprises a burner adapted to discharge hot gases of combustion over the upper portion of said molten material.
 3. An improvement as set forth in claim 1, wherein said cooling means is in sufficient proximity to the protruding lip to maintain the integrity thereof.
 4. An improvement as set forth in claim 3, wherein said cooling means comprises a container adapted for the circulation of water therethrough. 